High-peak-power ultrashort pulse lasers are currently in demand for laser micromachining. It is an effective technique to use ultra-large-mode-field fibers to amplify the power of ultrashort laser pulses, for realizing ultrashort output laser pulses with high beam quality and high peak power. Based on a 1030 nm mode-locked tunable fiber laser, multi-stages of all-fiber preamplifiers and ultra-large-mode-field rod-type photonic crystal fiber (PCF), the output properties of rod-PCF amplifiers are demonstrated. The amplifier delivers near-diffraction-limit 30 ps pulses with maximum peak power of 2.94 MW.